Gas Chromatography is an important and well developed technique of chemical analysis. Generally, in the Gas Chromatography technique a small aliquot of a sample containing several volatile components of interest dissolved in a volatile solvent is evaporated into a stream of mobile phase gas. This gas stream is then flowed past a relatively nonvolatile stationary phase and finally to a detector. The components of interest partition between the stationary phase and the mobile phase gas. If the partition coefficients of the components of interest are sufficiently different, then the components of interest are separated along the stationary phase. The separated components of interest are then detected and recorded as separate peaks on a chromatogram. The stationary phase can be coated on specially processed diatomaceous silica particles which are then packed into a tube to make a classical packed gas chromatography column. The stationary phase can also be coated on the interior wall of a capillary tube to make a capillary gas chromatography column. A large variety of materials have been used as the stationary phase in Gas Chromatography including lubricating oils and greases, waxes, polyesters, silicone oils, styrene polymers and LEXAN brand polycarbonate resin from General Electric.
The determination of organic acids in aqueous samples by Gas Chromatography is a problem for the gas chromatographer. The chromatography column deteriorates with repeated injections which causes the chromatographic peaks of the acids to tail and interferes with accurate quantitation of the acids. These problems are caused by the relatively high polarity of the organic acids and the effects of water and nonvolatile residues of the sample on the stationary phase and the stationary phase support. In the face of these problems, most gas chromatographers derivatize the organic acids to make methyl esters of them for injection into the gas chromatograph. Derivatizing the organic acids converts them into less polar compounds dissolved in a nonaqueous volatile organic solvent. However, derivatizing a sample is time consuming and expensive. It would be an advance in the art of Gas Chromatography if a stable method were developed wherein the organic acids in an aqueous sample could be determined without the need to derivatize them.